1. Field of the Invention
The present invention relates to a synthetic resin powder excellent in dispersibility in water.
2. Description of the Related Arts
An aqueous emulsion comprising an aqueous medium and polymer particles with small particle diameters dispersed therein has been employed in a variety of uses such as admixtures for cement or mortar, adhesives, binders for coating materials and the like. However, such an aqueous emulsion has involved the problems of a high transportation cost because of water as a dispersion medium contained in an amount of about 50% by weight, and disposal of the containers after use.
Under such circumstances, there is a demand for a synthetic resin powder which, although being in the form of powder during transportation, can easily be dispersed in water by adding water thereto under stirring at the time of use.
As a synthetic resin powder having dispersibility in water, there are known a vinyl ester polymer powder obtained by spray-drying an aqueous emulsion obtained through an emulsion polymerization of a vinyl ester monomer by the use of a polyvinyl alcohol (hereinafter abbreviated as "PVA") as a dispersant (disclosed in Japanese Patent Application Laid-Open No. 185606/1992); and a (meth)acrylic ester polymer powder and a diolefinic polymer powder each obtained by spray-drying an aqueous emulsion obtained through an emulsion polymerization of a (meth)acrylic ester monomer or a diolefinic monomer by the use of a low molecular weight surfactant as a dispersant.
However, any of the conventional synthetic resin powders has involved the problem of low dispersibility in water. In addition in the case of a vinyl ester polymer powder, there has been the problem of low alkali-resistance when used as an admixture for a mortar.